This invention relates to a socket for a pipe coupling adapted to be used for fluid, and more particularly to an inexpensive socket of simple structure which consists of a small number of components and can be assembled easily, and also to a socket having a structure capable of automatically maintaining a plug in a locked state (an inseparable state) and preventing a connection error.
Pipe coupling for fluid are well known from, for example, Japanese Patent Application KOKAI Publication No. 6-272795 and Japanese Utility Model Application KOKOKU Publication No. 56-16448.
The structure of the pipe coupling disclosed in Japanese Patent Application KOKAI Publication No. 6-272795 will be described briefly with reference to FIG. 10 which shows a cross section of the pipe coupling.
In the figure, reference numeral 101 denotes a socket body, in which a seal member 106, an elastic member 107, an inner collar 108, and an urging member 109 supported by the collar 108 are arranged. An outer collar 110 extending from the socket body 101 covers those elements. The outer collar 110 has an inclined surface having a larger diameter at its inner side and contacting the urging member 109, while the inner collar 108 can be slid from the outside.
When in this pipe coupling, insertion of a male member such as a plug or a pipe, not shown, has been started, the front end of the male member contacts the urging member 109, thereby moving the inner collar 108 and the male member to the left in the figure, against the urging force of the elastic member 107. When the urging member 109 has reached the large-diameter portion of the socket body 101, it moves to a radially outer space of the large-diameter portion, whereby the male member is inserted until its front end contacts a step 104, and positioned there. Further, when in this state, a pulling force has been applied to the male member, the urging member 109 is urged toward an inclined surface 113 of the outer collar 110 by the urging force of the elastic member 107, thereby urging the male member against the inclined surface 113. As a result, the male member is prevented from being pulled out of the socket.
The male member can be easily pulled out of the socket body by pushing the front end of the inner collar 108 toward the socket body 101 to enable movement of the urging member 109 to the large diameter portion of the socket body 101.
The structure of the pipe coupling described in Japanese Utility Model Application KOKOKU Publication No. 56-16448 will be described with reference to FIG. 11 which illustrates a cross section of the connector.
The pipe coupling comprises a plug 220 and a socket 230. The plug 220 has an insertion rod 223 with a peripheral groove 224 formed in a peripheral portion thereof and to be engaged with lock balls. The socket 230 is constituted of a main body 231, a sleeve 238, lock balls 241 and a spring 244. The spring 244 and the sleeve 238 are fitted in a cylindrical end chamber 236 formed in an end portion of the main body 231 of the socket 230. The sleeve 238 has a desired number of tapered radial holes 240 formed therein, in which the locking balls 241 are slidably inserted such that they can project from the inner-diameter portion of the sleeve 238. The portion of each lock ball which is opposite to the projecting portion is engaged with an escape groove 243, which has a tapered wedge surface 242 constituted of a peripheral portion of the inner wall of the cylindrical end chamber 236 in the main body 231. A groove is formed in one of the front end surface 231a of the main body 231 and a front end collar 237 incorporated in the sleeve 238, and a pin is provided on the other of them. The axial length of each of the groove and the pin is made to correspond to a distance over which the sleeve slides. As a result, the sleeve 238 is retreated against the elastic force of the spring 244 to release the lock balls 241 and enable attachment and detachment of the plug 220, only when the sleeve 238 is rotated with respect to the main body 231 such that the pin is engaged with the groove.
However, when in the case of the first-mentioned pipe coupling, the outer and inner collars 110 and 108 are assembled, the inner collar 108 with the urging member 109 is inserted into the outer collar 110 which has a uniform diameter as indicated by reference numeral 111, and then the outer collar 110 is cramped to form the inclined surface 113. Thus, the assemblage requires the cramping step and a cramping machine, which is a great obstacle to simplification of the assemblage or reduction of the assemblage cost. Further, the pipe coupling does not have a lock mechanism, and therefore if a force is applied from the outside to the inner collar 108 when the pipe coupling is assembled, it is possible that the urging force of the urging member will be released and the pipe will come out of the socket.
On the other hand, when in the case of the latter pipe coupling, the sleeve 238 is inserted into the socket 230, the lock balls 241 fall from a hole (not shown) formed in the socket into the tapered hole of the sleeve 238, and thereafter the hole in the socket 230 is blocked. Therefore, a great number of assemblage steps are required, which is disadvantageous for reducing the assemblage cost. Moreover, although the pipe coupling includes a lock mechanism which consists of the groove and the pin for preventing the detachment of the plug 220 in the connected state, the locking function of this lock mechanism is effected by the operator rotating the sleeve 238 after the connection of the socket is completed. Therefore, if the lock operation is forgotten, the plug 220 will come out of the socket 230 when an unintentional force has been applied to the sleeve 238 to push it within the socket 230.